1. Field of the Invention
The present invention relates to a cutter, such as a tabletop circular saw for cutting wooden boards.
2. Description of the Related Art
There has been known a cutter with a circular blade and a laser generator. The laser generator irradiates the workpiece with a laser light to indicate the position where the cutting is to be performed. The operator then uses the circular blade to cut the workpiece material at the position indicated by the laser light.
Japanese Utility-Model-Application Publication No. SHO-62-150019 discloses a cutter with a blade positioned above a workpiece and a laser generator fixed on the blade support at a position above the blade. Before cutting the workpiece, the user draws a mark on the workpiece to indicate the position on the workpiece to be cut. The user then aligns the laser light emitted from the laser generator with the mark on the workpiece, and lowers the blade to cut the workpiece.
The laser generator disclosed in Japanese Utility-Model-Application Publication No. SHO-62-150019 is fixed at the blade support. Therefore, if the laser light is not actually in alignment with the location that the blade cuts, the user must attempt to compensate for this positional difference by intentionally shifting the laser light out of alignment with the cutting position mark on the workpiece before cutting the workpiece. This increases the possibility that the workpiece will not be cut in the desired cutting position.
West German Patent Publication No. 3406904 discloses a cutter provided with a laser generator mounted on a slide bar. The laser generator can be freely slid horizontally along the slide bar to adjust position where the laser light irradiates the workpiece. However, minute adjustment of where the laser light irradiates the workpiece is difficult with this configuration.
U.S. Pat. Nos. 5,285,708 and 5,375,495 disclose cutters, each having a cutting portion that is disposed above the workpiece, and a laser generator that is disposed above and ahead of the cutting blade. A rail is suspended above the cutting blade so as to extend in a widthwise direction of the cutting blade. A groove is formed in the laser generator to fit in the rail. The laser generator is guided by along the rail so can easily moved in the horizontal direction. However, if the groove in the laser generator and the rail have a poor fit with gaps therebetween, then horizontal movement of the laser generator will be unstable so that the cutting position cannot be accurately indicated using the laser.
Next, a conventional mechanism for adjusting alignment of a laser light with a vertical reference line Y and with a horizontal reference line X will be explained with reference to FIGS. 1 (a) to 3. A cylindrical laser generator 70 is supported in a support member 71 by a fixing screw 72. The fixing screw 72 presses the laser generator 70 downward in the support member 71. The support member 71 is fixed to a base by two bolts 74, 74. One bolt 74 passes through a circular hole 76 and the other bolt 74 passes an elongated hole 77.
As shown in FIGS. 1 (a) and 1 (b), when laser light L1 from the cylindrical laser generator 70 is to be aligned with a vertical reference line Y, the fixing screw 72 is loosened and the cylindrical laser generator 70 is rotated within the support member 71 until the laser light L1 is aligned with the vertical reference line Y. Once alignment is achieved, the fixing screw 72 is retightened to fix the cylindrical laser generator 70 in place in the support member 71.
As shown in FIG. 2, when the laser light L1 is to be aligned with a horizontal reference line X, the bolts 74, 74 are loosened and the support member 71 is pivoted around the circular hole 76 within the horizontal plane. When the laser light L1 is aligned with the horizontal reference line X, then the bolts 74, 74 are tightened to fix the support member 71 in place.
However, because the tip of the fixing screw 72 is not completely flat, the cylindrical laser generator 70 might be moved out of alignment when the fixing screw 72 is tightened. When this happens, the operator must repeat the adjustment process until the laser light L1 is accurately aligned with the vertical reference line Y.
Also, when the bolt 74 is tightened, the support member 71 might move because the contacting surface of the support member 71 or the bolts 74 are slanted. In this case also, the operator must repeat the adjustment process until the laser light L1 is accurately aligned with the horizontal reference line X.